Air filters are generally known in the art and are employed in a variety of contexts including internal combustion engines, gas compressors and heating and ventilation systems. Designed to remove particulate matter from the air, a typical air filter is composed of a filtering material, often paper or foam, and a frame or housing that supports the filtering material. Typically an air filter is placed in the path of an air flow, such as proximate an air intake.
For an air filter to function properly and effectively, the air flow path should be directed toward and forced through the filtering portion of the air filter so that impurities in the air are removed. Thus, an air filter should be arranged to maximize air flow through the filter portion and to minimize the air flow around the filter edges. When an air flow bypasses an air filter, the performance of the filtration system is diminished, irrespective of the quality of air filter used. Therefore, it is important that an air filter be properly fitted for its intended application so as to ensure air flow through the filter portion. Ventilation ductwork and filter banks may vary in dimensions and, as a result, an air filter that may be of appropriate size for one application may not be suitable for an alternate application. To avoid the requirement of custom fitted air filters, there is a need for an air filter that can be adaptively fitted to spaces of varying dimensions while continuing to provide exceptional performance.
In some applications, particularly those related to commercial and industrial operations, the ventilation ducts may be quite large. Typically, several air filters are used side-by-side, sliding into air handlers. A single very large air filter for such use would likely be prohibitively expensive, cumbersome to install, and/or difficult to support. Thus, an array of air filters arranged adjacent to one another is typically employed as a filter bank. Traditional air filters of a filter bank, as slidably installed into a traditional air handler, often have a small gap disadvantageously therebetween. As such, some percentage of air flow may avoid being filtered by the filter bank prior to being circulated throughout the building.
Thus, whenever multiple air filters are juxtaposed one to another, a potential problem arises: the possibility of air flow through gaps between adjacent air filters. Bypassing the filtering portion of an air filter, air containing particulate matter including allergens and impurities may circulate under pressure throughout a building, exposing employees, patrons, or inhabitants to the harmful effects of its contaminants. Even when the gap between filters is narrow relative to the filter width, the volume of unfiltered air delivered to a building over time may be sufficient to produce detrimental effects on air quality. The effects may be particularly hazardous to people with asthma, allergies or other respiratory conditions.
As the efficiency of air filters increases, with some filters operating at 99.9% efficiency, the detrimental effects caused by unfiltered air flowing through a ventilation system becomes even more significant. Furthermore, in addition to adverse effects on individuals and operations within a building structure, unfiltered air flow may also induce mechanical problems within the ventilation system itself. Dust particles may be deposited on the heating and cooling coils, clogging the coils and impeding proper ventilation system operation. Cleaning such coils is both time consuming and expensive. Thus, there is a need for an air filter that prohibits an air stream from passing through gaps between air filters in a filter bank, thereby essentially preventing the flow of unfiltered air into a building.
In striving to attain healthy, high quality air for domestic and commercial environments, a high quality air filter, such as an HEPA filter, is often employed. However, HEPA filters may also be quite expensive, particularly when a large number of them are required for a filter bank. Further, although a HEPA filter may remove 99.9% of the particulates present in an air stream, it is first necessary that the air stream pass through the filter in order for success. A less expensive tactic than installation of HEPA filters for improving air quality is to decrease the volume of air permitted to bypass a filtration system. In this manner, cheaper, less efficient filters may be used to achieve the goal of high air quality. Thus, there is a need for inexpensive filters that may be easily installed in a manner that reduces air flow around the filters, thereby preventing the gross by-pass of filters and thereby increasing the overall air quality without requiring the use of expensive filter devices.
In the past, improvements have been suggested for filtering devices and the prevention of air flow therearound. One type of design is directed toward prevention of air bypass in a filter bank and a filter assembly, wherein as filter panels are inserted through an access opening in a filter bank, they are connected in side by side relation with “I”-shaped connectors. Sides of adjoining filter panels are inserted into opposed channels of the “I”-shaped connectors, wherein the positioning of the “I”-shaped connector helps prevent air bypass between the sides of adjacent filter panels. Although adequate for its intended purpose, such a design is disadvantageous in view of the present invention due to the requirement of using a connector piece separate from the filter itself.
Because the connector piece is inserted separately from the air filter, such filter installation process would disadvantageously be more time-consuming and cumbersome than that of installing filters alone. There is also the risk that an installer may inadvertently drop a connector piece into the filter bank and be forced to extract and reposition it, prolonging the installation process. In addition, installation may be dependent upon having an adequate supply of both connector pieces and air filters on site, possibly requiring installers to transport an increased volume of materials and supplies to installation sites.
Another type of filter design is that of a filter cartridge made of an accordion fold pack which can be inserted in a frame and used to filter air in ventilating systems. The filter cartridge can be cut to a desired size and sealed with sealing elements disposed at the end faces. The sealing elements fit into an insert opening of a frame or housing so that their end edges lie sealingly against the housing wall. The sealing elements may be variously shaped and extended outward, however, they are designed to seal the cartridge and fit it within a housing; thus, such a cartridge does not address the need for blocking air flow between multiple framed cartridges.
Another type of filter is intended for use in a kitchen range hood, wherein a boxlike frame is defined by a first U-shaped cross-section frame member and a second, inversely U-shaped cross-section frame member. Each frame member is provided with ridges used for fitting the members together to form a single filtration device. The ridges may also be used for joining adjacent filtration devices together. However, such ridges, typically composed of stainless steel, are designed to maintain a predetermined shape and dimension, and adjoining filtration devices are separated by a predetermined distance. As a result, the positioning of adjacent filters is not adjustable in a manner that may accommodate variably sized filter locations.
Therefore, it is readily apparent that there is a need for a filtration device that is adjustable, and that inhibits the undesirable passage of air about the peripheral edges.